1. Field of the Invention
The present invention relates to a reusable filter assembly containing removable and disposable filter elements, usually comprising a pleated paper element and an inner cavity filled with granular activated carbon and/or other materials. The filter assembly may be used to remove contaminants from liquids of all types, but it particularly addresses the filtration of dry cleaning solvent.
2. Description of the Prior Art
Until recently, most filters, including those used within the dry cleaning industry, were manufactured in a sealed housing made of metallic or other rigid materials that enclose the various filter elements such as paper, activated charcoal and clay pellets. The filter materials are designed to absorb various contaminants from liquids used for various purposes, e.g. cleaning and lubricating. Eventually, the filters become saturated and are unable to absorb any further contaminants and must be replaced. Since the filter assemblies are sealed, the complete assembly must be removed and a new one put in its place.
Disposal of this entire assembly creates several problems. Often the contaminants contained within a saturated filter unit are hazardous in nature and must be extracted from the sealed filter assembly prior to their proper disposal in a land fill. Disposal of the housing within a land fill adds non-degradable bulk to the land fill. The disposal of these rigid housings is expensive, and a waste of natural resources.
The following inventions are examples of sealed filters used in the dry cleaning industry:
______________________________________ Brucken, et al. U.S. Pat. No. 3,178,025 McMichael U.S. Pat. No. 3,189,179 Suchy U.S. Pat. No. 3,219,191 Hartley U.S. Pat. No. 3,263,812 Tuffnell U.S. Pat. No. 3,493,117 Giampalmi, Jr., et al. U.S. Pat. No. 3,730,347 Bauer U.S. Pat. No. 3,836,005. ______________________________________
An extensive field for utilization of filters is related to the filtration of the lubricating oil used within internal combustion engines. In this field, devices incorporating reusable filter elements have been known for a number of years; however, these filters are of a very different structure than those used within the dry cleaning industry as dictated by their different use. Examples of this type filter follow:
______________________________________ Eberle U.S. Pat. No. 3,085,688 Hultgren U.S. Pat. No. 3,260,367 Wood, et al. U.S. Pat. No. 3,282,429 Scavuzzo, et al. U.S. Pat. No. 3,333,703 Johnson U.S. Pat. No. 3,615,018 Russo U.S. Pat. No. 3,630,374 Cote, Jr. U.S. Pat. No. 4,228,011 Medley, III U.S. Pat. No. 4,802,979. ______________________________________
The development and widespread use of reusable filter assemblies within the dry cleaning industry have met with problems which limit complete acceptance of their use. One such problem relates to contamination of the filtered fluid during removal and replacement of the filter elements. Two examples of inventions intended to resolve this type problem are as follows:
______________________________________ Cooper U.S. Pat. No. 4,133,763 Tafara U.S. Pat. No. 4,253,959. ______________________________________
Another problem relates to ease of access for removal of the filters:
Smith, U.S. Pat. No. 4,138,337, discloses a system for separating the filter assembly into two parts for ease of removal from the process housing;
Cook, U.S. Pat. No. 3,595,398, utilizes a hinged side opening;
Tokar, et al., U.S. Pat. No. 4,647,373, utilizes a "peel away" paper filter medium; and
Ball, U.S. Pat. No. 3,542,202, utilizes a quick release mounting system which attaches the cartridge to the housing.
Another major problem relates to proper sealing between the elements and the filter assembly to prevent unfiltered liquid from bypassing the filter elements and re-entering the treated fluid stream. Close, U.S. Pat. No. 3,486,626, addresses this problem by providing a complex clamping and sealing means. Barrington, U.S. Pat. No. 4,810,379, seeks to solve this problem by providing two sealing means at either end of the paper filter element with one of the sealing means being removable from the core in order to permit replacement of the element. This invention however does not provide protection for the paper filter assemblies during insertion in the housing. Brucken, et al., U.S. Pat. No. 3,198,334 discloses a removable filter to be used in a home washer/dry cleaning apparatus in which the sealing system is incomplete as fluid is permitted to bypass the filter system.